This invention relates to an adjustable jet propulsion unit for a watercraft and more particularly to an improved arrangement for adjusting the position of a jet propulsion unit in a watercraft, supporting the jet propulsion for its movement and effective operation of the jet propulsion unit regardless of its position and also for adjusting the trim of a jet propelled watercraft.
Jet propulsion units have been proposed for powering watercraft and have a number of well known advantages. When the jet propulsion unit is mounted within a tunnel in the underside of the watercraft, a very good looking craft results. However, the positioning of the jet propulsion unit in the tunnel gives rise to certain servicing difficulties. In addition, it is desirable to insure that the jet propulsion unit may be raised out of the body of water in which the watercraft resides when the jet propulsion unit is not used for propulsion purposes. This will insure against incrustation of the jet propulsion unit and other disadvantages. A variety of devices have been proposed for moving the position of the jet propulsion unit and raising it out of the body of water in which the watercraft is operating when it is not being employed to propel the watercraft.
In addition to the aforenoted feature, it is well known in watercraft to provide some form of trim adjustment to adjust the trim of the watercraft to suit varying purposes. For example, the trim may be adjusted to improve the planing posture of the boat according to the rider's weight and rider's position, to improve posture according to wave condition and boat speed and also to trim for improved straight running or turning operations. Where a jet propulsion unit is used to propel a watercraft and it is movable and also a movable trim adjustment is incorporated, the structure becomes quite complicated and expensive.
It is, therefore, a principal object of this invention to provide an improved jet propelled watercraft having a movable jet propulsion unit and an integral trim adjustment.
It is a further object of this invention to provide a jet propulsion unit for a watercraft that embodies an integral trim adjustment.
If the jet propulsion unit is moved to change the trim condition of the watercraft, certain other problems arise. That is, it is desirable to insure that the water inlet opening of the jet propulsion unit is effectively sealed even when the trim condition is changed. Unless good sealing is provided around the water inlet opening of the jet propulsion unit, poor efficiency may result due to leakage around the water inlet opening.
It is, therefore, a further object of this invention to provide an improved arrangement for a movable jet propulsion unit that will provide good sealing around the water inlet regardless of the trim position of the jet propulsion unit.
When the trim of the jet propulsion unit is changed, there are additional problems in connection with the design. As is well known, jet propelled watercraft are normally steered by employing a pivotally supported steering nozzle at the discharge of the jet propulsion unit. This gives rise to substantial side thrusts on the jet propulsion unit when turning. If a movable support is employed, it must be capable of absorbing these large steering side thrusts.
It is, therefore, a further object of this invention to provide an improved and rigid support for a trim adjusted jet propulsion unit.
It is a further object of this invention to provide an improved side thrust taking arrangement for a movably supported jet propulsion unit.